Device authentication for wireless charging

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This application is a continuation of U.S. patent application Ser. No. 18/335,738, filed Jun. 15, 2023, which is a continuation of U.S. patent application Ser. No. 15/844,124, filed Dec. 15, 2017, now U.S. Pat. No. 11,701,976, issued Jul. 18, 2023, the contents of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

0002This disclosure relates generally to batteries and charging systems, and in particular to authenticating devices for wireless charging.

BACKGROUND INFORMATION

0003Battery powered devices such as drones, robots, submarines, satellites, electric cars, electric trucks, electric bikes, and other devices and vehicles may require battery charging. Wireless charging of these battery powered devices may offer reduced down-time and increase deployment efficiencies of the devices. Authenticating devices to facilitate wireless charging of the devices may be desirable to increase the security and/or efficiency of a wireless charging system.

BRIEF DESCRIPTION OF THE DRAWINGS

0004Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

0005<figref idref="DRAWINGS">FIG. <b>1</b></figref> is an example system that includes a plurality of wireless chargers and devices that can receive wireless energy from the wireless chargers to charge batteries of the devices, in accordance with an embodiment of the disclosure.

0006<figref idref="DRAWINGS">FIG. <b>2</b></figref> illustrates an example wireless charger including a communication interface and a transmit charging coil to deliver wireless energy to a receive charging coil, in accordance with an embodiment of the disclosure.

0007<figref idref="DRAWINGS">FIG. <b>3</b></figref> illustrates an example device that includes a wireless communication interface, a receive charging coil, and a propulsion mechanism, in accordance with an embodiment of the disclosure.

0008<figref idref="DRAWINGS">FIG. <b>4</b></figref> illustrates an example system that includes a wireless charger and a device configured to receive wireless energy from the wireless charger, in accordance with an embodiment of the disclosure.

0009<figref idref="DRAWINGS">FIG. <b>5</b></figref> illustrates a flow chart of an example process of identifying a wireless charger availability to charge a vehicle, in accordance with an embodiment of the disclosure.

0010<figref idref="DRAWINGS">FIG. <b>6</b></figref> illustrates a flow chart of an example process of dual-band communication for authenticating a device for wireless charging, in accordance with an embodiment of the disclosure.

0011<figref idref="DRAWINGS">FIG. <b>7</b></figref> illustrates a system including a wireless power transmitter and a wireless energy receiving module including a receive charging coil, in accordance with an embodiment of the disclosure.

0012<figref idref="DRAWINGS">FIG. <b>8</b></figref> includes an example impedance network, in accordance with an embodiment of the disclosure.

0013<figref idref="DRAWINGS">FIG. <b>9</b></figref> illustrates a flow chart of an example process of authentication for wireless charging, in accordance with an embodiment of the disclosure.

0014<figref idref="DRAWINGS">FIG. <b>10</b></figref> illustrates an example quadcopter having a receive charging coil, an example transmit charging coil included in a charging mat, and a charger coupled to drive the transmit charging coil, in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

0015Embodiments of a system, apparatus, and method of identifying wireless charging availability and authenticating devices for wireless charging are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

0016Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

0017Throughout this specification, several terms of art are used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

0018Many electronic devices include a battery that can be charged and recharged. Many times, the battery of the device is recharged by connecting the device to a charger with a charging wire. With conventional manual or mechanical re-charging, a mechanical connection is required to plug the device in for charging, and the physical connection comes apart when charging is complete. Automatically making and breaking mechanical connections has the following problems: (1) it is unreliable (often the operation fails due to sensing or actuating errors); (2) it leads to wear of contacts/connectors, which fail after a certain number of plug/unplug cycles; (3) it adds cost and complexity to the system, since some form of robot arm, human intervention or mechanical contact is needed to accomplish the plugging and un-plugging (and often these mechanisms must produce large amounts of force, adding to its cost and complexity); and (4) the additional mechanical parts in the charging mechanism are a further source of system-level unreliability, as the exposed ohmic contacts are prone to corrosion and are affected by water and humidity due to the environmental conditions. Thus, some contexts benefit from wirelessly charging a device to reduce human intervention and increase reliability.

0019In a particular illustrative context, drones used in aerial photography, are typically human supervised. When the drone runs out of power, a person plugs the drone into a charger. To enable new, autonomous drone applications, such as unattended, automatic daily inspection of a field or bridge, with the human operator absent, it is desirable for drones to be able to charge themselves.

0020In some system implementation, there may be a plurality of devices and a plurality of wireless chargers for charging those devices. When the devices are also vehicles having propulsion to navigate to the wireless chargers to gain contactless power, the system may improve efficiency from coordinating the charging of the devices at particular wireless chargers. In embodiments of the disclosure, a wireless charger may provide charging station data that allows the devices to locate the wireless charger to receive contactless power. The charging station data may also provide intelligence, such as a charging status of the wireless charger, so that the device will have charging availability of a particular wireless charger. The devices may navigate to a wireless charger based on the location of the wireless charger and/or the charging availability of the wireless charger. The device may receive the charging station data (e.g. location and/or charging availability) of more than one wireless charger and select and navigate to one of the plurality of wireless chargers based at least in part on the charging station data.

0021Emerging applications that may benefit from the disclosure include aerial, mobile, and aquatic robots. “Drones” are aerial vehicles, typically quad-copters with 4 (or more) electrically driven rotors. Aerial vehicles can also be embodied by fixed-wing unmanned aircraft driven by electrical motors. Conventional drones may typically operate for 10 minutes to 40 minutes before needing to recharge. Mobile robots drive along a surface using one or more electric motors to drive wheels and move the device. Mobile robots are used in many consumer, industrial, medical, retail, defense and security applications today. Aquatic robots drive above or below the surface of water using turbines or buoyancy pumps to propel the device in three-dimensional space. All of these types of robotic devices typically have batteries on the device that need to be recharged. Of course, devices such as forklifts, golf carts, electric vehicles, autonomous vehicles, and other devices may also benefit from wireless charging to receive contactless power in accordance with embodiments of this disclosure.

0022<figref idref="DRAWINGS">FIG. <b>1</b></figref> is an example system <b>100</b> that includes a plurality of wireless chargers <b>111</b> and devices <b>101</b> that can receive wireless energy from the wireless chargers <b>111</b> to charge batteries of the devices <b>101</b>, in accordance with an embodiment of the disclosure. <figref idref="DRAWINGS">FIG. <b>1</b></figref> includes wireless chargers <b>111</b>A, <b>111</b>B, and <b>111</b>C (collectively referred to as wireless chargers <b>111</b>) and devices <b>101</b>A, <b>101</b>B, and <b>101</b>C (collectively referred to as devices <b>101</b>). Device <b>101</b>A is an aerial drone, device <b>101</b>B is an electric car, and device <b>101</b>C is a land-based robot. Electric car <b>101</b>B may be an autonomous car in some embodiments. Of course, system <b>100</b> may include a plurality of devices <b>101</b>A, <b>101</b>B, and/or <b>101</b>C and other devices or vehicles could be included in system <b>100</b>.

0023In embodiments of the disclosure, wireless chargers <b>111</b> may “broadcast” charging station data for use by devices <b>101</b>. The charging station data may include a location of the wireless charger or a charging station identifier that can be used to identify a location of the wireless charger. The charging station data may also include charging availability data of the wireless charger. For example, if the wireless charger is presently charging a device, this may be reflected in the charging availability data so that device(s) <b>101</b> will be informed that a particular wireless charger is currently occupied. The devices <b>101</b> may receive the “broadcast” from a plurality of wireless chargers and then navigate to a particular wireless charger from the plurality of wireless chargers based at least in part on the data provided in the broadcasts from the plurality of wireless chargers. The devices may also take into account wind data, geographical data, and remaining battery capacity of the device, for example.

0024In <figref idref="DRAWINGS">FIG. <b>1</b></figref>, wireless charger <b>111</b>A broadcasts via communication channel <b>142</b>A, wireless charger <b>111</b>B broadcasts via communication channel <b>142</b>B, and wireless charger <b>111</b>C broadcasts via communication channel <b>142</b>C. Also in <figref idref="DRAWINGS">FIG. <b>1</b></figref>, device <b>101</b>A receives data via communication channel <b>141</b>A, device <b>101</b>B receives data via communication channel <b>141</b>B, and device <b>101</b>C receives data via communication channel <b>141</b>C. In some embodiments, the broadcast(s) of the wireless chargers <b>111</b> are relayed to the devices <b>101</b>A via a communication network <b>103</b>. Communication Network <b>103</b> may include any network or network system such as, but not limited to, the following: a peer-to-peer network; a Local Area Network (LAN); a Wide Area Network (WAN); a public network, such as the Internet; a private network; a cellular network; a wireless network; a wired network; a wireless and wired combination network; and a satellite network.

0025Communication channels <b>141</b> and <b>142</b> may include or be routed through one or more wired or wireless communication utilizing IEEE 802.11 protocols, Bluetooth, SPI (Serial Peripheral Interface), 12c (Inter-Integrated Circuit), USB (Universal Serial Port), CAN (Controller Area Network), cellular data protocols (e.g. 3G, 4G, LTE, 5G), optical communication networks, Internet Service Providers (ISPs), a peer-to-peer network, a Local Area Network (LAN), a Wide Area Network (WAN), a public network (e.g. “the Internet”), a private network, a satellite network, or otherwise.

0026In one illustrative embodiment, one or more wireless chargers <b>111</b> utilize an Ethernet connection as communication channel <b>142</b> and “broadcast” charging station data to a server <b>122</b> that is included in communication network <b>103</b>. Server <b>122</b> computer may be located remotely in a data center or located local to the wireless charger <b>111</b>. Server <b>122</b> may then send the data to the device(s) <b>101</b> via cellular network <b>121</b> or satellite network <b>123</b>, for example. Of course, when device(s) <b>101</b> receive the charging station data from a satellite, communication channel <b>141</b> is satellite communication channel and when device(s) <b>101</b> receive the charging station data from a cellular tower, communication channel <b>141</b> is a cellular communication channel.

0027In one embodiment, server <b>122</b> may aggregate charging station data from multiple wireless chargers <b>111</b> and forward the aggregated data to devices <b>101</b>. In one embodiment, server <b>122</b> may filter the charging station data by location of the wireless charger and only forward to the devices <b>101</b> the charging station data from wireless chargers that are within a certain distance of the device. The device may report a location (e.g. GPS location) to the server <b>122</b> for the purposes of filtering the charging station data that is forwarded to the device <b>101</b>. For example, a device may only receive charging station data for wireless chargers <b>111</b> that are within 5 miles of the device. Of course, other distances may be used as a filter.

0028In one illustrative embodiment, one or more wireless chargers <b>111</b> use a cellular communication channel <b>142</b> to “broadcast” charging station data and the charging station data is received by the device(s) <b>101</b> on a cellular communication channel <b>141</b>.

0029In one illustrative embodiment, wireless charger(s) <b>111</b> communicate directly with devices <b>101</b> and communication network <b>103</b> is not utilized. Rather, wireless charger(s) <b>111</b> may broadcast a wireless signal that is received by devices <b>101</b>. For example, wireless charger <b>111</b> may broadcast a WiFi signal on communication channel <b>142</b> and that same WiFi signal may be received directly by device(s) <b>101</b>. In some embodiments, the device(s) <b>101</b> may initiate an initial handshake to establish wireless communications with the wireless charger(s) <b>111</b> before the wireless charger(s) <b>111</b> “broadcast” their charging station data to the device(s) <b>101</b>. In other embodiments, the wireless charger(s) <b>111</b> may initiate an initial handshake to establish wireless communication with the device(s) <b>101</b> before the wireless charger(s) “broadcast” their charging station data to the device(s) <b>101</b>.

0030<figref idref="DRAWINGS">FIG. <b>2</b></figref> illustrates an example wireless charger <b>211</b> including a communication interface <b>220</b> and a transmit charging coil <b>205</b> to deliver wireless energy to a receive charging coil, in accordance with an embodiment of the disclosure. Wireless charger <b>211</b> includes wireless power transmitter <b>209</b> that includes a driver <b>207</b> coupled to the transmit charging coil <b>205</b>. Driver <b>207</b> drives a signal onto transmit charging coil <b>205</b> to facilitate wireless energy delivery to a receive charging coil configured to receive the wireless energy. The receive charging coil may be included in or attached with a device <b>101</b>. Wireless charger <b>211</b> also includes processing logic <b>243</b>, location sensor <b>257</b>, sense module <b>253</b>, and memory <b>251</b>. Memory <b>251</b> may store a charging station identifier of the wireless charger <b>211</b> and other data and/or instructions for execution by processing logic <b>243</b>.

0031Processing logic <b>243</b> is coupled to wireless power transmitter <b>209</b>. Processing logic <b>243</b> may control driver <b>207</b> to adjust the output of transmit charging coil <b>205</b>. Processing logic <b>243</b> is communicatively coupled to location sensor <b>257</b>, in <figref idref="DRAWINGS">FIG. <b>2</b></figref>. In one embodiment, location sensor <b>257</b> is a global positioning satellite (GPS) sensor providing GPS coordinates to processing logic <b>243</b>. Processing logic <b>243</b> is also communicatively coupled to sense module <b>253</b> in <figref idref="DRAWINGS">FIG. <b>2</b></figref>. Sense module <b>253</b> may include one or more proximity sensors, image sensors, or thermal cameras. The proximity sensor, image sensors, or thermal cameras may be positioned to detect the presence of humans, animals, or interfering objects. When a human, animal, or interfering object is sensed, processing logic <b>243</b> may disable the wireless charging of wireless charger <b>211</b> for safety purposes. Sense module <b>253</b> may also detect the presence of a proximate device that is being charged by wireless charger <b>211</b>. When a device is currently being charged by wireless charger <b>211</b>, processing logic <b>243</b> may update charging availability data of the charger <b>211</b> to reflect the charging availability of the wireless charger <b>211</b>.

0032Processing logic <b>243</b> is communicatively coupled to communication interface <b>220</b>. Communication interface <b>220</b> may include one or more separate communication interfaces. Communication interface <b>220</b> may include wired (e.g. Ethernet) and wireless (e.g. WiFi, cellular, Bluetooth, and/or RFID) communication interfaces. In the illustrated embodiment, communication interface <b>220</b> includes a wireless interface <b>223</b> configured for IEEE 802.11 communication and a radio frequency identification (RFID) interface <b>225</b>. RFID interface <b>225</b> may include an RFID “reader” that transmits RFID challenge signals. Communication interface <b>220</b> may send and receive data via one or more communication channels <b>242</b>. Wireless charger <b>211</b> may send and/or receive data <b>273</b> (e.g. charging station data) via communication channel <b>242</b>. In some embodiments, communication channel <b>242</b> is a wireless communication channel using a time division multiple access (TDMA) protocol to communicate with multiple devices and performs a clear-channel-assessment to ensure that the wireless communication channel <b>242</b> is not already occupied by other proximate communication systems (e.g. WiFi or remote control). This allows multiple devices to communicate with charger <b>211</b>, if needed.

0033<figref idref="DRAWINGS">FIG. <b>3</b></figref> illustrates an example device <b>301</b> that includes a wireless communication interface <b>320</b>, a receive charging coil <b>303</b>, and a propulsion mechanism <b>384</b>, in accordance with an embodiment of the disclosure. Device <b>301</b> also includes a wireless energy receiving module <b>393</b>, a battery <b>395</b>, a memory <b>307</b>, a measurement module <b>330</b>, and a location sensor <b>353</b>. Battery <b>395</b> may include multiple battery cells. In one example, battery <b>395</b> includes six battery cells. Battery <b>395</b> may include lithium-ion, nickel cadmium, or other battery chemistry. Wireless energy receiving module <b>393</b> includes a receive charging coil <b>303</b>, rectifier circuitry <b>315</b>, and power regulator <b>335</b>. Wireless energy received by receive charging coil <b>303</b> is rectified by rectifier <b>315</b> and regulated by power regulator <b>335</b> to charge battery <b>395</b> in the illustrated wireless energy receiving module <b>393</b> of <figref idref="DRAWINGS">FIG. <b>3</b></figref>. Rectifier <b>315</b> may include a full-wave bridge rectifier and power regulator <b>335</b> may include a PMIC (power management integrated circuit) such as a linear regulator, switching power supply, and/or switching regulator.

0034Processing logic <b>313</b> is coupled to wireless energy receiving module <b>393</b>. Processing logic <b>313</b> may control wireless energy receiving module <b>393</b> to adjust the charge/discharge of battery <b>395</b>. Additionally, processing logic <b>313</b> may receive electrical measurements from wireless energy receiving module <b>393</b>. Processing logic <b>313</b> is also coupled to measurement module <b>330</b> that may measure a voltage or a current of battery <b>395</b>. Measurement module <b>330</b> may include an analog-to-digital converter coupled to measure the voltage of battery <b>395</b> and/or a voltage representative of a current of battery <b>395</b>. Memory <b>307</b> is communicatively coupled to processing logic <b>313</b> in <figref idref="DRAWINGS">FIG. <b>3</b></figref> and processing logic <b>313</b> may read and write to memory <b>307</b>. Data and instructions to be executed by processing logic <b>313</b> may be stored in memory <b>307</b>. Location sensor <b>353</b> is coupled to processing logic <b>313</b> to provide a location of device <b>301</b>. In one embodiment, location sensor <b>353</b> is a GPS sensor and provides GPS coordinates to processing logic <b>313</b>.

0035Processing logic <b>313</b> is communicatively coupled to communication interface <b>320</b>. Communication interface <b>320</b> may include one or more separate communication interfaces. Communication interface <b>320</b> may include wired (e.g. Ethernet) and wireless (e.g. WiFi, cellular, Bluetooth, and/or RFID) communication interfaces. In the illustrated embodiment, communication interface <b>320</b> includes a wireless interface <b>323</b> configured for IEEE 802.11 communication and a radio frequency identification (RFID) interface <b>325</b>. RFID interface <b>325</b> may include an RFID “tag” that generates an RFID response signal when queried by an RFID challenge signal from an RFID reader. Communication interface <b>320</b> may send and receive data via one or more communication channels <b>341</b>. Device <b>301</b> may send and/or receive data <b>372</b> (e.g. charging station data) via communication channel <b>341</b>.

0036Propulsion mechanism <b>384</b> is coupled to be driven by processing logic <b>313</b>. Processing logic <b>313</b> may drive propulsion mechanism <b>384</b> based on data received from communication interface <b>320</b>, measurements of wireless energy receiving module <b>393</b>, and/or locations provided by location sensor <b>353</b>. Propulsion mechanism <b>384</b> may include one or more propellers for flight or underwater navigation. Propulsion mechanism <b>384</b> may include wheels and corresponding transmission or torque conversion hardware in the case of electric vehicles, for example. In some embodiments, propulsion mechanism may include tracks in the context of forklifts or land-based robots for example. Other propulsion mechanism examples may be used in accordance with embodiments of this disclosure.

0037The term “processing logic” (e.g. <b>243</b> or <b>313</b>) in this disclosure may include one or more processors, microprocessors, multi-core processors, and/or Field Programmable Gate Arrays (FPGAs) to execute operations disclosed herein. In some embodiments, memories (not illustrated) are integrated into the processing logic to store instructions to execute operations and/or store data. Processing logic may include analog or digital circuitry to perform the operations disclosed herein. A “memory” or “memories” (e.g. <b>251</b> or <b>307</b>) described in this disclosure may include volatile or non-volatile memory architectures.

0038<figref idref="DRAWINGS">FIG. <b>4</b></figref> illustrates an example system <b>400</b> that includes wireless charger <b>211</b> and device <b>301</b> configured to receive wireless energy from the wireless charger <b>211</b>, in accordance with an embodiment of the disclosure. <figref idref="DRAWINGS">FIG. <b>4</b></figref> shows that wireless charger <b>211</b> may communicate with device <b>301</b> via communication channels <b>443</b>, <b>444</b>, and/or <b>445</b>. In some embodiments, all three of communication channels <b>443</b>, <b>444</b>, and <b>445</b> are utilized. Transmit charging coil <b>205</b> may deliver wireless energy <b>457</b> to receive charging coil <b>303</b>. Wireless power transmitter <b>209</b> may be driven by processing logic <b>243</b> to selectively transmit the wireless energy <b>457</b> to receive charging coil <b>303</b> as a technique to encode data in the transmission of wireless energy <b>457</b>. Similarly, wireless energy receiving module <b>393</b> may be driven by processing logic <b>313</b> to selectively reflect the wireless energy <b>457</b> as reflected wireless energy <b>456</b> and encode data into the reflected wireless energy <b>456</b>. Hence, communication channel <b>445</b> may include one-way and/or two-way communication between wireless power transmitter <b>209</b> and wireless energy receiving module <b>393</b>.

0039<figref idref="DRAWINGS">FIG. <b>5</b></figref> illustrates a flow chart of an example process <b>500</b> of identifying a wireless charger availability to charge a vehicle, in accordance with an embodiment of the disclosure. The order in which some or all of the process blocks appear in process <b>500</b> should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel.

0040In process block <b>505</b>, a wireless charger (e.g. wireless charger <b>211</b>) determines a charging status of the wireless charger. Determining a charging status may include processing logic <b>243</b> receiving a status signal from sense module <b>253</b> that indicates whether a vehicle is currently being charged by wireless power transmitter <b>209</b>. The charging status of wireless charger <b>211</b> may be updated to indicate that a vehicle is being charged based on the status signal from sense module <b>253</b>. The status signal may be activated based on signals from the sensors included in sense module <b>253</b>. In one embodiment, determining a charging status includes measuring one or more electrical characteristics of an amplifier providing a signal to transmit charging coil <b>205</b>. An amplifier using significant power may indicate ongoing wireless charging and thus the charging status may be updated to indicate that a vehicle is being charged. In one embodiment, determining a charging status includes driving a challenge signal onto an RFID interface included in communication interface <b>220</b>. If a valid response from an RFID tag is received by the RFID interface, a vehicle having the RFID tag is proximate to wireless charger <b>211</b>.

0041In process block <b>510</b>, the wireless charger transmits its charging station data to vehicles. As described with respect to <figref idref="DRAWINGS">FIG. <b>1</b></figref>, the transmission of charging station data may include broadcasting the charging station data on different communication channels. The charging station data may include a location (e.g. GPS coordinates) of the wireless charger and/or a charging station identifier. The charging station data may also include a charging status of the wireless charger.

0042In process block <b>515</b>, a vehicle receives the charging station data. The charging station data may be received by the vehicle via a wireless communication channel <b>141</b>/<b>341</b>.

0043In process block <b>520</b>, a location of the wireless charger is determined by the vehicle based on the charging station data. If the charging station data includes a charging station identifier, the charging station identifier may be used by the vehicle to ascertain the location of the wireless charger. A relational database may have locations of wireless chargers corresponding to the charging station identifier, for example. The relational database may be stored in a memory of the vehicle (e.g. <b>307</b>) or be stored remotely and access by the vehicle using communication interface <b>320</b>, for example. If the charging station data includes GPS coordinates, for example, the location of the wireless charger can be determined from the GPS coordinates.

0044In process block <b>525</b>, the propulsion mechanism (e.g. <b>384</b>) of the vehicle is driven to navigate the vehicle to the wireless charger based at least in part on the charging status and the location of the wireless charger. In one embodiment, driving the propulsion mechanism to navigate the vehicle includes driving the vehicle to the wireless charger when the charging status indicates a charging availability to deliver wireless energy to the receive charging coil of the vehicle. If the charging status of the wireless charger indicates that the wireless charger is charging another vehicle, the vehicle may not navigate to that wireless charger. In one embodiment, the vehicle navigates to the closest wireless charger that is unoccupied (not currently charging another vehicle). In one embodiment, the propulsion mechanism may be driven to navigate to a particular wireless charger based on the location of the wireless charger, the charging status of the wireless charger, and/or a battery voltage of the vehicle. If the battery voltage of the vehicle is particularly low and the range of the vehicle is therefore limited, the vehicle may navigate to the closest wireless charger even though the wireless charger is currently charging another vehicle, for example.

0045In process block <b>530</b>, the vehicle receives wireless charging from the wireless charger and in process block <b>535</b>, the wireless charger provides wireless energy to the vehicle. Of course, process blocks <b>530</b> and <b>535</b> may happen contemporaneously.

0046In process block <b>540</b>, the vehicle updates its charging status to indicate that it is currently charging a vehicle. In process block <b>545</b>, the wireless charger transmits charging station data that includes its updated charging status to vehicles. The charging station data may be transmitted by the communication interface <b>220</b>.

0047In one embodiment, process <b>500</b> further includes the vehicle transmitting, with a wireless communication interface, a navigation message to the wireless charger. This transmission may occur subsequent to process block <b>520</b> being executed. The navigation message may indicate that the vehicle is navigating toward the wireless charger for wireless charging. The wireless charger may receive the navigation message from the vehicle. In response to receiving the navigation message from the vehicle, the wireless charger may transmit queue data that includes a number of vehicles that are navigating toward the wireless charger. Providing queue data to vehicles via this transmission may allow the vehicles to determine a preferable wireless charger to navigate to. For example, if the queue data from a first wireless charger indicates that six vehicles are navigating to a first wireless charger while queue data from a second wireless charger indicates only two vehicles are navigating to the second wireless charger, this may factor into a navigation decision by the vehicle.

0048As described briefly above, each vehicle may receive charging station data from a plurality of wireless chargers and a vehicle may determine which wireless charger to navigate to for wireless charging based on receiving the charging station data from multiple wireless chargers. Hence, in one embodiment of process <b>500</b>, the vehicle may receive second charging station data that includes a second charging status of a second wireless charger. The vehicle may determine a second location of the second wireless charger and navigate the vehicle either to the first wireless charger or the second wireless charger based at least in part on the charging status and location of the first wireless charger and the second charging status and second location of the second wireless charger. The vehicle may receive charging station data from many (more than two) wireless chargers and select from among the many wireless chargers and navigate to the selected wireless charger based on the charging station data from all the many wireless chargers.

0049In one embodiment of process <b>500</b> where the vehicle is receiving charging station data from multiple wireless chargers, the initial charging station data include a first remaining charge time of a device being charged by the initial wireless charger and the second charging station data includes second remaining charge time of a device being charged by the second wireless charger. Here, even if two wireless chargers are at roughly the same distance from a vehicle and the charging status of each of the wireless chargers indicates they are currently charging a device, a remaining charge time of the device may assist the vehicle in determining which wireless charger to navigate to. The wireless charger (e.g. <b>211</b>) may generate a remaining charge time from a battery voltage measurement of a vehicle being currently charged and reported to the wireless charger via the communication interface (e.g. <b>320</b>) of the vehicle presently being charged. The battery voltage may be measured by a measurement module (e.g. <b>330</b>) of the vehicle. In one embodiment, the wireless charger may generate a remaining charge time from a battery current measurement, battery state of health, battery state of charge, or battery capacity remaining of a vehicle being currently charged and reported to the wireless charger via the communication interface (e.g. <b>320</b>) of the vehicle presently being charged.

0050<figref idref="DRAWINGS">FIG. <b>6</b></figref> illustrates a flow chart of an example process of dual-band communication for authenticating a device for wireless charging, in accordance with an embodiment of the disclosure. The order in which some or all of the process blocks appear in process <b>600</b> should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel.

0051Wireless chargers servicing fleets of vehicles may need to authenticate whether a particular vehicle is authorized to be charged by the wireless charger. Various wireless communication protocols are vulnerable to being compromised by attacks from bad actors or even inadvertent access. Thus, authenticating schemes for authenticating devices and/or selecting devices for charging by wireless chargers may benefit from increased authentication and corresponding security.

0052In operation <b>603</b> of <figref idref="DRAWINGS">FIG. <b>6</b></figref>, a communication link is established between a wireless charger (e.g. <b>211</b>) and a device (e.g. <b>311</b>) configured to receive wireless energy from the wireless charger. In the example process <b>600</b>, operation <b>603</b> includes process blocks <b>605</b>, <b>610</b>, <b>615</b>, <b>620</b>, and <b>625</b>. However, alternatives to the illustrated process blocks may be used to establish a communication link between a wireless charger and a device.

0053In the illustrated example operation <b>603</b>, process block <b>605</b> includes transmitting a data query with a wireless interface of the wireless charger. In process block <b>610</b>, the data query is received by a wireless communication interface of the device. In process block <b>615</b>, a data response is transmitted by the wireless communication interface of the device and in process block <b>620</b>, the data response is received by the wireless communication interface of the wireless charger.

0054In process block <b>625</b>, the device is verified by the wireless charger. Verifying the device may include checking the data response against a list of verified devices where the data response includes a device identifier. In one embodiment, verifying the device includes comparing the data response to an expected response from devices that are authorized to be charged by the wireless charger. In example process <b>600</b>, after the device is verified, process <b>600</b> proceeds to process block <b>630</b>.

0055In process block <b>630</b>, an authentication challenge signal is driven onto a transmit charging coil (e.g. transmit charging coil <b>205</b>). The data query of process block <b>605</b> may be transmitted prior to the authentication challenge signal. In one embodiment, the data query is transmitted while the authentication challenge signal is driven onto the transmit charging coil. In one embodiment, driving the authentication challenge signal onto the transmit charging coil includes modulating at least one of a frequency or duty cycle of the authentication challenge signal. The authentication challenge signal may be driven within a second frequency range that is different from a first frequency range of the communication link established in operation <b>603</b>. In one embodiment, the authentication challenge signal is approximately 13.56 MHz and the communication link is approximately 2.4 GHz and utilizes IEEE 802.11 protocols. The authentication challenge signal driven onto the transmit charging coil may be approximately 13.56 MHz+/−7 kHz, 6.78 MHz+/−15 kHz, or 80-250 kHz. The communication link of operation <b>603</b> may utilize frequencies such as 400 MHz and 915 MHZ.

0056In process block <b>635</b>, the device measures at least one electrical attribute of the authentication challenge signal received by a receive charging coil (e.g. <b>303</b>) of the device. In one embodiment, the measured electrical attribute is a rectified voltage of the received authentication challenge signal on rectifier <b>315</b>. In one embodiment, the measured electrical attribute is a battery current supplied to charge a battery (e.g. <b>395</b>) of the device.

0057In one embodiment, the authentication challenge signal is encoded with data and measuring the electrical attribute of the authentication challenge signal includes performing a series of measurements to decode data encoded into the authentication challenge signal. For example, a series of measurements of the rectified voltage can decode digital values encoded into the authentication challenge signal.

0058In process block <b>640</b>, the measured electrical attribute(s) are transmitted to the wireless charger as an authentication response signal with the wireless communication interface of the device. The authentication response signal indicates a receipt of the authentication challenge signals since the authentication response signal includes electrical attributes/measurements of the authentication challenge signal.

0059In process block <b>645</b>, the wireless charger initiates a wireless energy delivery from the transmit charging coil of the wireless charger to the receive charging coil of the device when the received measured attributes are within a pre-determined range. For example, if a rectified voltage is the measured electrical attribute, the measured attribute would need to be within a particular voltage range for verification purposes for the wireless charger to initiate a wireless energy delivery. The pre-determined range may be a digital value when the authentication challenge signal is encoded with digital data and the measured attribute includes the digital data decoded by the device.

0060Process <b>600</b> thus facilitates a dual-band authentication of devices that are presented for wireless charging since the authentication includes both wireless communication at the first frequency range in addition to some measurement of an authentication challenge signal of a second frequency range different from the first frequency range. The specific hardware required to measure the authentication challenge signal decreases the likelihood that the authentication scheme of process <b>600</b> will be compromised by a bad actor or inadvertent access to wireless charging would be granted. Advantageously, the dual-band authentication of process <b>600</b> utilizes the transmit charging coil of the wireless charger and the receive charging coil of the device that are already configured to send and receive, respectively, wireless energy.

0061In some embodiment, additional verification procedures are performed prior to wirelessly charging the device with the wireless charger. The additional verification procedures may include security and safety procedures. In one embodiment, an RFID tag on the device is also verified by an RFID reader of the wireless charger to provide further assurance that the proximate device is authorized to be receiving wireless charging from the wireless charger.

0062<figref idref="DRAWINGS">FIG. <b>7</b></figref> illustrates a system <b>700</b> including a wireless power transmitter <b>741</b> and a wireless energy receiving module <b>793</b> including a receive charging coil <b>203</b>, in accordance with an embodiment of the disclosure. Example wireless power transmitter <b>741</b> may be included in wireless charger <b>211</b> and processing logic <b>243</b> may be coupled to control wireless power transmitter <b>741</b>. Wireless power transmitter <b>741</b> includes a driver <b>743</b> to generate a transmitter signal <b>744</b>. Amplifier <b>745</b> is coupled to receive the transmitter signal <b>744</b> from driver <b>743</b> and generate amplified transmitter signal <b>746</b> at an output of the amplifier <b>745</b>. Driver <b>743</b> may include a radio-frequency generator with a programmable amplitude, frequency or duty cycle. An amplifier voltage <b>732</b> and amplifier current <b>731</b> are provided to amplifier <b>745</b>. Voltage tuner <b>721</b> is coupled to adjust the amplifier voltage <b>732</b>. Voltage tuner <b>721</b> may include a switching power supply with a programmable voltage output. In one embodiment, voltage tuner <b>721</b> includes a programmable potentiometer that is controlled by processing logic (e.g. <b>243</b>). In embodiments where voltage tuner <b>721</b> is a programmable potentiometer, one node of the potentiometer may be coupled to the amplifier voltage <b>732</b> and the other node may be coupled to amplifier <b>745</b>. In one embodiment, a digital-analog converter (DAC) is included in voltage tuner <b>721</b> to adjust the amplifier voltage <b>732</b>. The DAC may be coupled to receive digital values from processing logic (e.g. <b>243</b>). Wireless power transmitter <b>741</b> also includes an impedance network <b>747</b> coupled to receive the amplified transmitter signal <b>746</b> and coupled to transmit an authentication challenge signal <b>748</b> onto transmit charging coil <b>205</b>. An impedance of the impedance network <b>747</b> may be adjusted to modulate the authentication challenge signal <b>748</b> that is driven onto transmit charging coil <b>205</b>.

0063The authentication challenge signal may also be modulated by adjusting the duty cycle, amplitude and/or the frequency of the transmitter signal <b>744</b> generated by driver <b>743</b>. In one embodiment, the authentication challenge signal may also be modulated by adjusting the amplifier voltage <b>732</b> provided to power amplifier <b>745</b>, which influences the magnitude of the authentication challenge signal.

0064Example wireless energy receiving module <b>793</b> includes receive charging coil <b>203</b>, an impedance network <b>763</b>, a rectifier <b>765</b>, and a power converter <b>767</b>. <figref idref="DRAWINGS">FIG. <b>7</b></figref> also includes a battery <b>395</b> having a battery voltage <b>772</b> and the battery <b>395</b> is coupled to the wireless energy receiving module <b>793</b>. Wireless energy receiving module <b>793</b> is an example wireless energy receiving module that may be included in device <b>301</b>. Impedance network <b>763</b> is coupled between receive charging coil <b>203</b> and rectifier <b>765</b>. Power converter <b>767</b> is coupled to generate converted voltage <b>768</b> and coupled to receive the rectified voltage <b>766</b> from rectifier <b>765</b>. One or more capacitors (not illustrated) and other filtering circuitry may be coupled to rectifier <b>765</b> to smooth rectified voltage signal <b>766</b>. Power converter <b>767</b> may include a linear regulator, switching power supply, or other de-de converters known in the art.

0065Wireless energy receiving module <b>793</b> also includes switches <b>753</b>(<b>1</b>), <b>753</b>(<b>2</b>), and <b>753</b>(<b>3</b>) coupled to receive converted voltage <b>768</b>. In <figref idref="DRAWINGS">FIG. <b>7</b></figref>, switches <b>753</b>(<b>1</b>), <b>753</b>(<b>2</b>), and <b>753</b>(<b>3</b>) are illustrated as transistors having gates <b>755</b>(<b>1</b>), <b>755</b>(<b>2</b>), and <b>755</b>(<b>3</b>), respectively. Gates <b>755</b>(<b>1</b>), <b>755</b>(<b>2</b>), and <b>755</b>(<b>3</b>) may be controlled by processing logic <b>313</b> when wireless energy receiving module <b>793</b> is included in device <b>301</b>. When switch <b>753</b>(<b>1</b>) is closed, battery current <b>771</b> charges battery <b>395</b>. In some embodiments, when switch <b>753</b>(<b>2</b>) is closed, converted voltage <b>768</b> is provided as device power <b>774</b> to a device that includes wireless energy receiving module <b>793</b>. When switch <b>753</b>(<b>3</b>) is closed, load <b>776</b> receives converted voltage <b>768</b>. In one embodiment, (not illustrated) the one or more of switches <b>753</b> are replaced with a conductor (e.g. copper trace) to provide converted voltage <b>768</b> directly to battery <b>395</b>, device power <b>744</b>, and/or load <b>776</b>.

0066<figref idref="DRAWINGS">FIG. <b>7</b></figref> shows a signal <b>281</b> representative of an authentication challenge signal received by wireless energy receiving module <b>793</b>. The actual waveform of a received authentication challenge signal may be different in practice depending on how much filtering is applied to the signal. For illustrations purposes, a signal similar to signal <b>281</b> may be present as rectified voltage <b>766</b>. Processing logic (e.g. <b>313</b>) may be coupled to sample the rectified voltage <b>766</b> at a given sampling time interval <b>783</b>. Processing logic <b>313</b> may include an analog-to-digital converter (ADC) to sample rectified voltage <b>766</b>. In one embodiment, a digital symbol is included in the authentication challenge signal. For signal <b>781</b>, the digital symbol may be the number <b>252</b> (binary 11111100) whereas the digital symbol for signal <b>782</b> may be <b>212</b> (binary 11010100). Processing logic that samples rectified voltage signal <b>766</b> may decode the digital symbol. An authentication response signal sent from device <b>301</b> to wireless charger <b>211</b> may include the digital symbol for authentication purposes, in some embodiments. The authentication response signal may be encoded into reflected wireless energy <b>456</b> and/or sent as data <b>372</b> via communication channel <b>341</b>.

0067In some embodiments, a time period t1 <b>785</b> that signal <b>781</b> is activated serves as the authentication challenge signals and the time period t1 <b>785</b> is measured by processing logic (e.g. <b>313</b>) and the time period t1 <b>785</b> is included in the authentication response signal. In some embodiments, a magnitude of signal <b>781</b> serves as the authentication challenge signals and the magnitude of signal <b>781</b> is measured by processing logic (e.g. <b>313</b>) and that magnitude is included in the authentication response signal. In some embodiments, the magnitude of an authentication challenge signal is measured at a plurality of moments in time and the plurality of measurements is included in the authentication response signal.

0068<figref idref="DRAWINGS">FIG. <b>8</b></figref> includes an example impedance network <b>860</b>, in accordance with an embodiment of the disclosure. Impedance network <b>860</b> may be used as impedance network <b>747</b> and/or <b>763</b>, although impedance network <b>860</b> is illustrated for use with impedance network <b>747</b> in <figref idref="DRAWINGS">FIG. <b>8</b></figref>. Example impedance network <b>860</b> includes capacitors <b>851</b>(<b>1</b>), <b>851</b>(<b>2</b>), and <b>851</b>(N) coupled to receive amplified transmitter signal <b>746</b>, where “N” is the number of capacitors in impedance network <b>860</b>. In the illustrated embodiment, each capacitor <b>851</b> is coupled to a corresponding switch <b>853</b>. In <figref idref="DRAWINGS">FIG. <b>8</b></figref>, switches <b>853</b>(<b>1</b>), <b>853</b>(<b>2</b>), and <b>853</b>(N) are illustrated as transistors having gates <b>855</b>(<b>1</b>), <b>855</b>(<b>2</b>), and <b>855</b>(N), respectively. Gates <b>855</b>(<b>1</b>), <b>855</b>(<b>2</b>), and <b>855</b>(N) may be controlled by processing logic <b>243</b> when impedance network <b>860</b> is included in impedance network <b>747</b>. When a switch <b>853</b> is off (open), its corresponding capacitor <b>851</b> does not influence amplified transmitter signal <b>746</b>. However, when a switch <b>853</b> is on (closed), its corresponding capacitor <b>851</b> will influence amplified transmitter signal <b>746</b>. Therefore, turning on and off switches <b>853</b> (via gate voltages <b>855</b>) will selectively add or subtract capacitance and thus influence amplified transmitter signal <b>746</b> that is driven onto transmit charging coil <b>205</b> as authentication challenge signal <b>748</b>. It is understood that impedance network <b>860</b> is an example for illustration purposes and that other impedance elements (e.g. resistors and inductors) can be used similarly to add or subtract impedance, in series or in parallel, to an impedance network to influence signal <b>746</b> and <b>748</b>. When impedance network <b>860</b> is included in impedance network <b>763</b>, gates <b>855</b>(<b>1</b>), <b>855</b>(<b>2</b>), and <b>855</b>(N) may be controlled by processing logic <b>313</b> to influence the impedance of receive charging coil <b>203</b>.

0069<figref idref="DRAWINGS">FIG. <b>9</b></figref> illustrates a flow chart of an example process of authentication for wireless charging, in accordance with an embodiment of the disclosure. The order in which some or all of the process blocks appear in process <b>900</b> should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel.

0070In process block <b>905</b>, a wireless data channel is established between a first wireless communication interface (e.g. <b>223</b>) included in a charger and a second wireless communication interface (e.g. <b>323</b>) included in a receiving device. The particular technique for establishing the wireless data channel may vary. In one embodiment, the technique disclosed in operation <b>603</b> of <figref idref="DRAWINGS">FIG. <b>6</b></figref> is utilized. WiFi, Bluetooth, Zigbee, Wireless HART, and/or other protocols may be used for the wireless data channel.

0071In process block <b>910</b>, transmit circuitry (e.g. <b>721</b>, <b>843</b><b>745</b>, and/or <b>747</b>) included in the charger drives an authentication challenge signal onto a transmit charging coil included in the charger. The authentication challenge signal is included in wireless energy <b>456</b> in this embodiment. In one embodiment, driving the authentication challenge signal onto the transmit charging coil includes modulating at least one of a frequency, amplitude, or duty cycle of the authentication challenge signal. In one embodiment, driving the authentication challenge signal onto the transmit charging coil includes adjusting an amplifier voltage of an amplifier (e.g. <b>765</b>) having an amplifier output coupled to the transmit charging coil. In one embodiment, driving the authentication challenge signal onto the transmit charging coil includes adjusting an impedance of an impedance network (e.g. <b>747</b>) coupled to the transmit charging coil. In some embodiments, some combination of adjusting the amplifier voltage or current of the amplifier, adjusting the impedance of the impedance network, and adjusting the duty cycle, amplitude and/or frequency of the authentication signal is utilized to generate a unique authentication challenge signal. On the receiving device, measuring the rectified voltage (e.g. <b>766</b>) and/or the battery current (e.g. <b>771</b>) may assist in measuring the authentication challenge signal.

0072In process block <b>915</b>, at least one electrical attribute generated by the authentication challenge signal being driven onto the transmit charging coil is measured. The at least one electrical attribute may be measured while the authentication challenge signal is being driven onto the transmit charging coil.

0073In one embodiment, the at least one electrical attribute generated by the authentication challenge signals being driven onto the transmit charging coil is measured on the receiving device. Measuring the at least one electrical attribute generated by the authentication challenge signals being driven onto the transmit charging coil may include measuring a receiver electrical attribute of an electrical component coupled to a receive charging coil of the receiving device. The receiver electrical attribute may be transmitted from the second wireless communication interface of the receiving device to the first wireless communication interface of the charger. In one embodiment, the receiver electrical attribute is a rectified voltage (e.g. <b>766</b>) from a rectifier (e.g. <b>765</b>) coupled to the receive charging coil.

0074In one embodiment, the at least one electrical attribute generated by the authentication challenge signals being driven onto the transmit charging coil is measured on the charger. For example, the amplifier voltage <b>732</b> or amplifier current <b>731</b> may be measured as the at least one electrical attribute when an authentication response signal is generated by modulating the impedance of receive charging coil <b>203</b>. In other words, measuring amplifier voltage <b>732</b> or amplifier current <b>731</b> while the authentication challenge signal is being driven onto transmit charging coil <b>205</b> is one technique for measuring the authentication response signal when the authentication response signal is generated by impedance modulation of impedance network <b>763</b>, for example. In this embodiment, the receiving device (e.g. <b>301</b>) may sense a signal on the receive charging coil <b>203</b>. Sensing a signal may include periodically sampling the rectified voltage <b>766</b> and comparing the sampling to a voltage threshold, for example. In response to sensing the signal, an impedance of impedance network <b>763</b> may be modulated to generate an authentication response signal. Modulating the impedance of receive charging coil <b>203</b> may be accomplished my opening and closing switch(es) <b>853</b>, for example. Wireless energy delivery is more efficient when the transmit charging coil and the receive charging coil are impedance matched. Thus, a higher amount of power is necessary to deliver wireless energy to the receive charging coil when the receive charging coil is impedance mismatched. Consequently, a higher amplifier current <b>731</b> provided to amplifier <b>745</b> may indicate an impedance mismatch (and less efficient wireless energy transfer) to the receive charging coil. A sagging amplifier voltage <b>732</b> may similarly indicate an impedance mismatch caused by the increase in amplifier current <b>731</b>. If a receiving device selectively matches and mismatches the impedance (e.g. using impedance network <b>763</b>) of receive charging coil <b>203</b>, it can effectively communicate an authentication response signal that can be measured by the power that the amplifier <b>745</b> requires to send the authentication challenge signal within wireless energy <b>457</b>.

0075In process block <b>920</b>, wireless energy delivery from the transmit charging coil to a receive charging coil of the receiving device is initiated based at least in part on the at least one electrical attribute.

0076In one embodiment, when a rectified voltage (e.g. <b>766</b>) is measured and transmitted back to the charger via the established wireless data channel, the charger verifies that the rectified voltage is within an expected range and subsequently initiates the wireless energy delivery. In one embodiment, when a series of electrical measurements of the amplifier voltage and/or current indicates a particular authentication response signal, the charger verifies the authentication response signal and subsequently initiates the wireless energy delivery.

0077<figref idref="DRAWINGS">FIG. <b>10</b></figref> illustrates an example quadcopter <b>1002</b> having a receive charging coil <b>1003</b>, an example transmit charging coil <b>1005</b> included in a landing pad <b>1021</b>, and a charger <b>1011</b> coupled to drive the transmit charging coil <b>1005</b>, in accordance with an embodiment of the disclosure. Charger <b>1040</b> may include the components of charger <b>211</b> except that transmit charging coil <b>205</b> is replaced with a similar transmit charging coil <b>1005</b> included in landing pad <b>1021</b>. In the illustrated embodiment of <figref idref="DRAWINGS">FIG. <b>10</b></figref>, receive charging coil <b>1003</b> is coiled around, or integrated into, leg <b>1013</b> of quadcopter <b>1002</b>. In some embodiments, some or all or legs <b>1013</b> of quadcopter <b>1002</b> may include coils <b>1003</b> to facilitate charging of a battery <b>1095</b> that powers quadcopter <b>1002</b>. The components of device <b>301</b> (excluding battery <b>395</b> and receive charging coil <b>303</b>) may also be included in quadcopter <b>1002</b> to facilitate charging of battery <b>1095</b>. It is appreciated by those skilled in the art that coils <b>1003</b> may be disposed somewhat remote from battery <b>1095</b> while still providing the energy via a wire to a wireless energy receiving module (e.g. <b>393</b>) that converts and provides the wireless energy to battery <b>1095</b>. When a plurality of receive charge coils <b>1003</b> are utilized, they may be coupled to the same rectifier (e.g. <b>315</b>) so that whichever receive charging coil(s) <b>1003</b> that are receiving the wireless energy can deliver the wireless energy to the rectifier.

0078In a land-based mobile robot system, wall-mountable enclosures that house a charger may be vertically mounted on walls for charging the land-based mobile robots. In an electric vehicle system, a floor-mounted enclosure may be utilized to house the charger (e.g. <b>211</b>) and the receive charging coil may be mounted in the belly of the vehicle to recharge the electric vehicle's battery or batteries.

0079In contexts where devices that include batteries are deployed in cold temperatures, battery performance of those devices may suffer from the cold temperatures. In some embodiments, the wireless power transfer system of this disclosure may be utilized to generate heat to keep electronics and batteries warmer to increase performance in colder environments.

0080In one embodiment, load <b>776</b> of <figref idref="DRAWINGS">FIG. <b>7</b></figref> is located proximate to battery <b>395</b> and warming the battery <b>395</b> includes a charger providing wireless energy <b>457</b> to receive charging coil <b>203</b> and providing converted voltage <b>768</b> to load <b>776</b> to generate heat to heat battery <b>395</b>. In this embodiment, processing logic (e.g. <b>313</b>) may keep switches <b>753</b>(<b>1</b>) and <b>753</b>(<b>2</b>) off while switch <b>753</b>(<b>3</b>) is turned on to provide converted voltage <b>768</b> to load <b>776</b> (e.g. resistor network spread around battery <b>395</b>).

0081In one embodiment, one or more of impedance network <b>763</b>, rectifier <b>765</b>, or power converter <b>767</b> is located proximate to battery <b>395</b> and warming the battery <b>395</b> includes a charger providing wireless energy <b>457</b> to receive charging coil <b>203</b>. These components will generate heat due to receiving the wireless energy <b>457</b> and thus heat up battery <b>395</b>.

0082In one embodiment, impedance tuning of impedance network <b>763</b> is utilized to warm battery <b>395</b>. Generally, impedance network <b>763</b> may be tuned to facilitate efficiency and reduce heat loss due to impedance mismatch between transmit charging coil <b>205</b> and receive charging coil <b>203</b>. However, where heating the battery <b>395</b> is a goal, the impedance of impedance network <b>763</b> may be adjusted to be purposely inefficient to produce heat for battery <b>395</b>. By mismatching the impedance of receive charging coil <b>203</b>, more wireless energy <b>457</b> is reflected as reflected wireless energy <b>456</b> and heat generation on receive charging coil <b>203</b> is a byproduct of the mismatched impedance. Hence, where receive charging coil <b>203</b> is disposed proximate to battery <b>395</b> and where impedance network <b>763</b> is controlled (e.g. by processing logic <b>313</b>) to create an impedance mismatch, receive charging coil <b>203</b> may beneficially generate heat for battery <b>395</b> from wireless energy <b>457</b>. In some embodiments, an impedance of impedance network <b>747</b> is adjusted to create an impedance mismatch between transmit charging coil <b>205</b> and receive charging coil <b>203</b> so that wireless energy <b>457</b> generates more heat on receive charging coil <b>203</b>.

0083In one embodiment, the magnitude of wireless energy <b>457</b> is increased so that the voltage generated on receive charging coil <b>203</b> is purposely higher than required to charge battery <b>395</b>. For example, if power converter <b>767</b> generates a converted voltage <b>768</b> of 12 VDC and is most efficient when rectified voltage is 14 VDC, the magnitude of wireless energy <b>457</b> may be increased such that rectified voltage <b>766</b> is 16 VDC so that power converter <b>767</b> generates more heat by stepping down a higher voltage (e.g. 16 VDC) to the 12 VDC for charging battery <b>395</b>. Increasing the magnitude of wireless energy <b>457</b> may include increasing the amplifier voltage <b>732</b> and/or increasing the gain of amplifier <b>745</b>. Increasing the magnitude of wireless energy <b>457</b> may also include increasing a duty cycle of transmitter signal <b>744</b>.

0084In one embodiment to warm battery <b>395</b>, the battery <b>395</b> is charged by turning switch <b>753</b>(<b>1</b>) on and subsequently battery <b>395</b> is discharged by coupling load <b>776</b> to battery <b>395</b> by closing switches <b>753</b>(<b>3</b>) and <b>753</b>(<b>1</b>). The charge/discharge functions can be cycled on and off to keep battery <b>395</b> warm. In one embodiment, warming the battery <b>395</b> includes increasing the battery current <b>771</b> by tuning the gate voltage <b>755</b>(<b>1</b>) so that the increased battery current <b>771</b> generates more heat/power from the electrical components between receive charging coil <b>203</b> and battery <b>395</b>.

0085In one embodiment, thermal sensor <b>799</b> (e.g. a thermistor) is disposed to provide a battery temperature of battery <b>395</b>. Processing logic <b>313</b> may periodically read thermal sensor <b>799</b> and when the thermal sensor <b>799</b> indicates that the battery temperature has reached a temperature threshold, processing logic <b>313</b> may send a message to a charger (e.g. charger <b>211</b>) to provide heat to battery <b>395</b> using wireless energy <b>457</b>. Both the charger and/or the receiving device that includes the battery <b>395</b> may go into a battery warming mode to facilitate warming of battery <b>395</b> so that the battery temperature at thermal sensor <b>799</b> climbs over the temperature threshold.

0086Embodiments of the disclosure include systems that allow for and facilitate autonomous operation of a wireless power system. A charger such as wireless charger <b>211</b> may operate in a system idle mode when no recognizable devices are in range of charging. In the system idle mode, a microcontroller included in processing logic (e.g. <b>243</b>) of the charger may be powered on, but the wireless power transmitter (e.g. <b>209</b>) may be in a low power state where wireless energy <b>457</b> is not being delivered. In system idle mode, the charger may continue to periodically broadcast charging station data and transmit the data queries described in association with process block <b>605</b>.

0087The charger may enter a heartbeat mode when activity is detected by the charger. Activity may be detected based on a successful establishment of a wireless communication channel as discussed in operation <b>603</b>. The heartbeat mode may include authenticating one or more devices (e.g. <b>311</b>) according to processes <b>600</b>.

0088Heartbeat mode may also include determining if a device is close enough to begin charging. To determine this, the device may measure the rectified voltage (e.g. <b>766</b>) and report the rectified voltage to the charger over a wireless communication channel. If the rectified voltage is within a pre-determined range, wireless power transfer is continued by the charger. In one embodiment, the battery voltage (e.g. <b>772</b>) of the device or amplifier current (e.g. <b>731</b>) of the charger is used to determine if the device is close enough to begin charging. Using the amplifier current may be advantageous in that it does not require a wireless communication channel to be established between the charger and the device. The charger may also perform measurements to determine whether a device is within a suitable charging distance. For example, the charger may measure an amount of power consumed by amplifier <b>745</b>. If the power level is above a pre-determined value, the receive charging coil of the device may be too close to the transmit charging coil or there may be an interfering device present.

0089Furthermore, if a battery is already fully charged or severely discharged, charging the battery may cause damage to the battery and/or charger. Therefore, a device that measures electrical attributes of the battery (e.g. <b>772</b>) and reports them back to the charger allows the charger to make informed decisions about whether to proceed to a power ramp-up mode of charging the battery. This information also allows the charger to intelligently decide which device to power, when two or more devices are present at a charger. Each device that is proximate to a charger may communicate task priorities such as time until a next task (e.g. a drone flight mission), which may allow the charger to prioritize charging of one of the devices.

0090The charger (e.g. <b>211</b>) and device (e.g. <b>301</b>) may receive and transmit a variety of information that can be stored in their memories. Data stored on the device may be queried by the charger over the wireless communication link. A device may download data or firmware updates via a wireless communication link provided by charger <b>211</b>, in some embodiments. Therefore, the charger can provide remote updates, security codes, flight plans, task instruction, and other data to the device while the device is charging or at least proximate to the charger.

0091Examples of data that the charger may record are: 1) number of connections with each device; 2) total amount of charging time for each receiver; 3) battery voltage when the device leaves the charger; 4) battery voltage when the device returns to the charger; 5) timestamps of when each device leaves the charger; 6) build configuration for the charger and the devices; 7) security authentication codes; 8) timestamp of when each device returns to the transmitter; 9) total amount of time the device is away from the charger; 10) voltage and current measurements to monitor power transfer; 11) error states of the charger and/or devices; and 12) preventative maintenance alerts. This data may be transferred from the charger to a network for cloud storage or cloud computing via WiFi or Ethernet, for example. The data may also be wirelessly communicated to the devices.

0092Examples of data that the device may record includes: 1) number of charge cycles for the device battery; 2) total energy delivered to the device battery; 3) time-stamped measurements of anomalies in the device battery; 4) total energy consumed by the device from the battery; 5) total energy delivered to the device battery; 6) the device battery state of charge; 7) battery lifetime cell charging/balancing statistics; 8) build configuration for the device; and 9) security authentication codes. This data may be wirelessly transferred from the device to the charger and ultimately to a network for cloud storage or cloud computing.

0093When the authentication of heartbeat mode is completed, the charge may proceed to a power ramp-up mode for devices that are within sufficient operating range of the charger and safety conditions have been met. In one embodiment, the wireless energy receiving module begins to ramp-up the amount of power it delivers to the device or battery of the device. Consequently, the charger increases the amount of power it delivers to the wireless energy receiving module. The wireless energy receiving module may have the ability to control the output voltage (e.g. <b>768</b>) or current limit of the power delivered to the device. These two parameters can be pre-determined or updated dynamically over the wireless communication link between the charger and the device. The output voltage may be set once at the beginning of the ramp-up mode, but the current limits may be incrementally increased over a period of time. Increasing the current limit allows more current to flow to the device. As the current limit increases, the amount of power being provided by the charger must increase to maintain sufficient power delivery to the device. To do this effectively in real-time, the device may continuously monitor the rectified voltage that is sent back to the charger over the wireless communication channel. If the rectified voltage drops below a predetermined threshold, the charger will increase the amount of power it transmits wirelessly. If the rectified voltage exceeds a threshold, the charger may decrease the amount of power it transmits wirelessly. Other parameters can also be used for this determination, including but not limited to battery voltage, battery current, power amplifier voltage, power amplifier current, and reflected energy. Any of these parameters and/or measurements may be communicated via a wireless communication channel to provide a feedback loop.

0094After the battery current achieves a predetermined threshold, the power ramp-up mode may transition to a steadier battery charging mode having a constant current, which may be the maximum charge current for the battery. This predetermined current threshold may be maintained throughout the constant-current battery charging mode. The device may continuously monitor the state of the battery and may transition from constant-current to constant-voltage charging as the battery voltage approaches the float voltage (i.e. charge termination voltage) configured for the battery. If the power received by the device reduces (which could be caused by the device shifting around or temperature change of the charger causing it to reduce the amount of power it can deliver), the wireless energy receiving module can dynamically reduce the current delivered to the battery. This feedback loop may also ensure that the wireless energy receiving module will always have a supply of power greater than the power it provides to the battery or device. The charger may continue to monitor the power delivered and decrease the power as the charging power tapers off in constant-voltage charging mode. The receiver may alert the transmitter to terminate charging the battery when the current being drawn by the battery drops below 1/10th of the configured constant-current charging rate (the C/10 rate). To prevent over-charging the battery for the case where the devices is drawing more current from the battery than the C/10 rate, the wireless energy receiving module may pause charging after a configured time has elapsed (e.g. I to 3 hours), measure the battery voltage and terminate charging if the voltage is with the Recharge Threshold (or approximately 95%) of the float voltage configured for the battery. If the battery voltage is more than the Recharge Threshold below the float voltage, the end of a charge timer may be reset and charging may be resumed. Any of these fault detection or battery conditions can be communicated from the wireless energy receiving module to the device that will allow the device to make an independent decision or a decision can be recommended from the wireless energy receiving module based on that information. An example of such system could be a wireless energy receiving module detecting a battery depletion of an aerial drone. The system can alert the aerial drone to make a safe landing based on a battery fault detection.

0095The processes explained above are described in terms of computer software and hardware. The techniques described may constitute machine-executable instructions embodied within a tangible or non-transitory machine (e.g., computer) readable storage medium, that when executed by a machine will cause the machine to perform the operations described. Additionally, the processes may be embodied within hardware, such as an application specific integrated circuit (“ASIC”) or otherwise.

0096A tangible non-transitory machine-readable storage medium includes any mechanism that provides (i.e., stores) information in a form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable/non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

0097The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.

0098These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.